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Turnagain Arm tidal power envisaged
TEC report indicates high power potential; company conducts environmental and technical studies while seeking further funding
Alan Bailey for Petroleum News
In its latest annual report to the Federal Energy Regulatory Commission, Tidal Energy Corp. has presented its view of the tidal energy potential of Alaska's Turnagain Arm and an overview of some studies required for a tidal power development. The company has been seeking federal and state funding assistance for the studies.
For several years the company has been promoting the concept of a tidal power facility near the entrance to Turnagain Arm, to use the major tidal currents in the arm as a source of renewable energy.
In principle, the tidal energy could generate most of the electricity used by the Railbelt electric utilities. Some of the power could potentially be used to manufacture green hydrogen.
In 2021 FERC issued a preliminary permit to TEC, to give the company the exclusive right to study the feasibility of developing a major tidal power system.
The annual report to FERC by Christopher D.L. Lee, president and CEO of TEC, says that, based on Pacific Northwest National Laboratory water speed data for the area between Point Possession and Fire Island, early estimates of potential power output range from 547,500 megawatt hours per year to 3.7 million megawatt hours per year, with an installed capacity range of 312 megawatts to 1,062 megawatts.
Funding for studies TEC said that it has early approval through the Department of Energy's Testing Expertise and Access for Marine Energy Research program for the funding of three studies and anticipates completing these studies in early 2024. One of the studies consists of partnering with PNNL on a characterization of the biological and environmental aspects of the Turnagain Arm location, in particular to enable permitting for the deployment of tidal technologies.
The second study, also with PNNL, involves the computer modeling of water speeds and turbulence. The third study, partnering with the Alaska Center for Energy and Power and the National Renewable Energy Laboratory at the University of Alaska Fairbanks, involves water speed measurements to confirm the water speed modeling.
The company is also seeking funding for bathymetry and geotechnical studies.
The company has been applying for funding through the Alaska Energy Authority's Renewable Energy Fund. During last year's funding cycle, AEA did not recommend funding support for a bathymetry study but did support funding for consultation on permitting. However, the funding did not gain approval by the Legislature.
This year the company is applying for a $2 million Renewable Energy Fund grant for similar studies.
TEC is also preparing an application to the US Department of Energy Water Technologies Office for funding assistance under a federal funding opportunity for tidal and water current research and development.
The funding opportunity results from the bipartisan Infrastructure Investment and Jobs Act that was passed by Congress last year.
Design concepts Originally TEC had envisaged a tidal power system involving the placement of two 8-mile tidal bridges across Turnagain Arm, with one bridge stretching west from Fire Island and the other bridge placed at least five miles from the first bridge. Each bridge would have held multiple subsea turbines.
However, the company determined that, because of its size and potential environmental impact, the bridge concept would not have obtained an environmental permit.
Consequently, the company changed the design concept to the construction of six tidal barrage-style power stations, each about half a mile long and 300 feet wide.
However, the company subsequently determined that this design would also prove too environmentally invasive. Instead, the company has focused on a turbine field concept, using fields of individual turbines that could be seafloor or surface based, depending on a determination of an appropriate engineering solution.
The turbine fields would be placed several miles apart, to soften the impact of the turning of tidal currents on the total power output.
In a previous report to FERC Lee said that his company had identified three companies that offered turbines capable of generating power at a megawatt scale and that two of these companies had signed memoranda of understanding for feasibility analysis and resource assessments for siting in Turnagain Arm.
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